"I must say I find this to be a quite misantropic attitude in general."
That's circular reasoning, even if disguised. You are (implicitly) saying that selfishness is morally wrong, and therefore people who propose that every act is out of selfishness have a negative worldview (a world view in which everybody is morally wrong), and therefore they are misanthropic (because of your own assumption that selfishness is morally wrong and that considering everybody morally wrong is about only seeing the bad in people). If you remove the moral presupposition on 'selfishness' from your argument, your conclusion to misanthropy (which has an inherent moral judgement) doesn't hold any more.
And just to point out you don't have to go the Ayn Rand route to come up with an alternative.....
I believe our virtues are built out of our vices. Selfishness can clearly cause harmful actions, but it can also be a strong motivator for building a common good as well, and these are not mutually exclusive. Indeed every vice I can think of can be built into a virtue.
In this view it isn't virtuous or not to be selfish, but rather the manner in which we are selfish (or lustful, or envious, or angry, etc) that creates virtue or vice. Order your vices and they become your virtues.
And just to point out you don't have to go the Ayn Rand route to come up with an alternative...
No, but one should probably consider what Rand had to say about selfishness, when considering discussions of this nature. Her ideas make a lot of sense; and have been a positive influence on a lot of people.
I guess the way I look at Rand is a using her works is ideally a bit like using Nietzsche (and indeed I see a lot of continuity in these two thinkers). Their actual ideas are interesting solely as an exercise in inverting the way we normally think about things and thus creating a void where we can create something new.
The nice thing about playing with inverting opposites is that it is useful in destroying what we thought we know. I wouldn't treat the inversion as any more valuable than what it inverts though.
I'm not exactly an Ayn Rand scholar, but AIUI, Rand was influenced by Nietzsche and claimed him as such an influence early in her career... but at some point later in her career she broke ways with him and adopted a more negative outlook on his ideas. At any rate, I can definitely see some overlap or correspondence in their works (disclaimer: I'm also not a Nietzsche scholar).
That's circular reasoning, even if disguised. You are (implicitly) saying that selfishness is morally wrong, and therefore people who propose that every act is out of selfishness have a negative worldview (a world view in which everybody is morally wrong), and therefore they are misanthropic (because of your own assumption that selfishness is morally wrong and that considering everybody morally wrong is about only seeing the bad in people). If you remove the moral presupposition on 'selfishness' from your argument, your conclusion to misanthropy (which has an inherent moral judgement) doesn't hold any more.